A large number of drugs and other medicaments are routinely prepared and administered to patients in a health care facility. Sometimes, two components of a therapeutic composition are required to be mixed immediately prior to administration. One method for mixing therapeutic compositions immediately prior to administration includes mixing two solutions in a mixing vessel, whereupon the mixture is drawn into a syringe, and the resulting mixed composition is then applied to an appropriate site of the patient. However, this process is often cumbersome, a significant amount of the drug may be lost, and the time between the mixing and the application is often too long with sensitive compositions (i.e., compositions that, upon mixing, must be immediately administered).
Another method for mixing therapeutic compositions immediately prior to administration employs two syringes that are clamped together. Output ends of the syringes are inserted into a Y-shaped coupling device having two input openings and a single output opening. Mixing occurs in the Y-shaped coupling device or in a needle connected to the single output end of the Y-shaped coupling device. However, with this type of arrangement, control over the degree of mixing does not exist and the degree of mixing, therefore, may be inadequate.
Another method for mixing therapeutic compositions immediately prior to administration includes coupling two syringes with an independent coupling means, thereby allowing the contents of one syringe to be mixed with the contents of the other coupled syringe. The independent coupling means, however, provides a space where there is very little agitation due to plug flow of the contents. The contents, therefore, do not mix well. Additionally, when the syringes are uncoupled (i.e., disengaged), the contents have to be aspirated out of the independent coupling means or they will be lost. In addition, the independent coupling means must be removed and discarded before attaching a needle to the delivery or injection syringe.
U.S. Pat. No. 4,994,029 (the '029 patent) discloses a syringe mixer and injector device formed of an injector and an adapter having opposed interconnectable nozzles on their facing ends and sockets and a short tubular spike in each socket to penetrate the stopper of a vial when connected to that socket. See, the '029 patent col. 2, 11. 24-31. It is among the additional objects of the invention to provide such a device which can be used with a receiving vial charged with a medicament solid or liquid, and a charging vial charged with a medicament liquid for one-way transfer to the receiving vial for admixing the medicaments therein without retransfer to the charging vial. Id. at col. 2, 11. 38-24 and col. 6, 11. 23-30. The injector inner end has a connection, provided with a nozzle recess containing a tapered, e.g. central, spout defining the inner terminus of pathway 5 and a lock connection formation, such as a luer lock tab, arranged to form a male connection formation for interconnecting releasably with mating parts on adapter 30. Col. 4, 11. 5-12. Since the '029 patent explicitly discloses that the system is made for one-way transfer, without recharging the charging vial, it would not be suitable for the recombination of materials between two syringes.
Since the system disclosed in the '029 patent was not contemplated for multiple-pass use (i.e., recombination of materials between two syringes), the skilled artisan would not use the '029 patent disclosure for a syringe system wherein multiple-pass use is desired. This is so because a system not contemplated for multiple-pass use, that is nonetheless employed for multiple-pass use, can result in an appreciable amount of sample loss (e.g., leakage). This is especially troublesome when the drug is expensive (e.g. leuprolide acetate). This is also troublesome since the U.S. Food and Drug Administration (FDA) requires that the health care professionals administer an active ingredient in a precise and known amount. Obviously, this requirement cannot be met when there is an appreciable amount of sample loss due to the syringe assembly.
U.S. Pat. No. 6,223,786 (the '786 patent) is directed to devices and methods for mixing medication and filling an ampule of a needle-less injector prior to an injection, which includes a reagent holder and a diluent holder. See, the '786 patent, col. 2, 11. 6-15. The diluent holder includes a plunger which is depressed to load the diluent from the diluent holder into the reagent holder to mix with the reagent to produce a liquid medication for filling the ampule of the needle-less injector. Id. at col. 2, 11. 20-25. In further embodiments, the reagent holder further includes a reagent plunger rod. Id. at col. 2, 11. 24-26. There is no disclosure or suggestion either explicitly or implicitly to include a male or female end forming a fluid tight engagement. In fact, the only engagement disclosed is a thread like engagement without any mention to fluid tightness. Moreover, the engagement disclosed by the '786 cannot be locked, as the threaded engagement has no means of locking.
In the most simplistic embodiment, the '786 patent discloses a four part system: diluent holder, support brushing, reagent holder, and the needleless injector; while the '029 patent discloses a four part system: injector, plunger vial, adaptor and charging vial. The presence of multiple (e.g., four) components increases the likelihood of human error when mixing and administering a drug. Additionally, the presence of multiple components increases the likelihood of an occurrence of sample loss (e.g., leakage).
Thus, there is a need for a syringe system wherein components of a composition can be easily mixed by the end user without losing a significant amount of mixed composition during the mixing process and wherein the mixed composition can be easily and rapidly administered to a patient. Such a syringe system will have a relatively few number of interconnecting parts, to minimize human error and to minimize sample loss. Additionally, the syringe system will effectively mix the contents located therein without sample loss, such that it will be approved by the FDA when used with drugs that must be administered in a known, discrete and precise amount (e.g., leuprolide acetate).